Astroblog: Comet C/2025 R2 (SWAN) is now at its brightest.

Tuesday, October 21, 2025

Comet C/2025 R2 (SWAN) is now at its brightest.


North-western sky on Tuesday, October 21 as seen from Adelaide at 21:05 ACDST (90 minutes after sunset, click to embiggen). Comet C/2025 R2 (Swan) is between the handle of the teapot of Sagittarius and the bright star Altair. The inset is the approximate binocular view of the comet at the time.	North-western sky on Sunday, October 26 as seen from Adelaide at 21:11 ACDST (90 minutes after sunset, click to embiggen). Comet C/2025 is close to the moderately bright star epsilon Aquarii not far from the obvious pair of alpha and beta Capricorni. The inset is the approximate binocular view of the comet at the time.	North-western sky on Wednesday, October 22 as seen from Adelaide at 21:05 ACST (90 minutes after sunset, click to embiggen). The track of the comet every three nights is shown the comet starts at aroun magnitude 6 and will slowly fade, and the waxing Moon will make it harder to see.

Comet C/2025 R2 (Swan) is is now at its brightest, around magnitude 6 (binoculars only), but it is well placed near some reasonably bright guide stars so it will be easy to find. It is currently a fuzzy disk in 10x50 binoculars. Although it is ~ magnitude 6, and theoretically visible to the unaided eye, it is still best in binoculars or a telescope. It has climbed high enough into dark skis to make spotting relatively easy.

The comet is now setting after midnight, so you have plenty of time to observe. at the beginning of the week the comet is between the handle of the teapot of Sagittarius and the obvious bright star Altair. Sart hopping along the line of brightish stars from the handle of the teapot towards the obvious bright star Altair should bring to the the comet. By the 24th it is just under the obvious part of stars alpha and beta Capricorni and within a binocular field of alpha Capricorni. By the 26th it is within a binocular field of the moderately bright star epsilon Aquarii. On the 29th and 30th it is within a binocular field of the moderately bright star beta Aquarii. The on 2 November it s almost on to of the brightish star alpha Aquarii (see the printable charts below).

more information can be found at https://www.aerith.net/comet/catalog/2025R2/2025R2.html see also https://www.minorplanetcenter.net/iau/MPEph/MPEph.html for an ephemeris (type C/2025 R2 in the ephemeris box).


Black and White printable chart of the western sky starting Tuesday, October 21 as seen from Adelaide at 21:05 ACDST (90 minutes after sunset, click to embiggen and print). The track of the comet over successive nights is shown (the comet starts around magnitude 6 and will fade over the month but still will be binocular visible).	Black and White printable chart suitable for binoculars of the comet for October 21 to October 24. (90 minutes after sunset, click to embiggen and print). Use in conjunction with the spotters chart.	Black and White printable chart suitable for binoculars of the comet for October 24 to October 30. (90 minutes after sunset, click to embiggen and print). Use in conjunction with the spotter chart.